Planetary transmission

ABSTRACT

A power shift transmission having planetary and countershaft gearsets, and clutch carriers for selectively transmitting power to and from the elements of the gearsets to selectively provide one of a multiplicity of speed ratios through the transmission.

United States Patent 1191 Crooks 1 June 19, 1973 [5 PLANETARYTRANSMISSION 2,932,202 4/1960 Rinkema 74/1563 x 3,065,643 11/1962 Market a1. 74/1563 [75] Invent James Cmoks, Mllwaukee 3,430,518 3/1969Auriol 74/705 73 Assignee; A|lis Cha|mel-s Corporation, 3,487,723 1/1970Piot 74/682 Milwaukee, Wis. 3,487,724 1/1970 MCIHtyIC et a1. 74/15.6 X[22] led: 1971 Primary Examiner-Arthur T. McKeon [21] App]. No.: 188,261Attorney-Arthur L. Nelson, Robert B. Benson and Charles L. Schwab [52]U.S. C1. 74/1563, 74/682, 74/705,

74/759 [57] ABSTRACT [51] Int. C1...Fl6h 37/00, F16h 37/06, F16h 57/10 Apower shift transmission havmg planetary and coun- [58] Field of Search74/682, 674, 705, tershaft earsets and clutch Carriers for Selective]74/15 63 g y transmitting power to and from the elements of the gearsetsto selectively provide one of a multiplicity of [56] References cuedspeed ratios through the transmission. UNITED STATES PATENTS 2,793,5335/1957 Swenfon et'al. 74/1563 10 Claims, 5 Drawing Figures 1 PLANETARYTRANSMISSION This invention relates to a planetary transmission and moreparticularly to a transmission having a countershaft gearset, a frontplanetary gearset with a front clutch carrier rotating coaxially forselective transfer of power to and from one of the elements of the ringgear, sun gear, or planetary carrier of said front planetary gearset anda dual pinion rear planetary gearset with a rear clutch carriertransferring power from the rear planetary gearset and the countershaftgearset to the output shaft.

Various power transmissions have been employed in vehicles, such as thecountershaft transmissions and planetary gear transmissions withmechanical and power shifting. While various types of transmissions havebasically certain inherent advantages, the primary function of thetransmission is to provide a suitable number of speed ratios for smoothtransmission of power through the transmission and smooth transitionfrom one gear ratio to another with maximum efficiency. Accordingly,this invention provides a combination of various types of transmissionswhich incorporate many of the advantages of each type of transmission.

It is an object of this invention to provide a planetary transmissionhaving a front planetary gearset and a rear dual pinion planetarygearset, and a countershaft gearset, together with rotating clutchcarriers on the front and the rear of the transmission rotatingconcentrically with the planetary gearsets with means for transferringpower to and from the elements of the gearsets for transmitting powerthrough the transmission at the selected speed ratio.

It is another object of this invention to provide a planetarytransmission having a front planetary gearset and a rear dual pinionplanetary gearset and a countershaft gearset with a clutch carrierrotating concentrically with each of the front and the rear planetarygearsets for selectively providing one of a plurality of power paths andspeed ratios through the transmission as selected by a control means.

It is a further object of this invention to provide a planetarytransmission having a front planetary gearset connected to the inputdrive shaft and a rear dual pinion planetary gearset and a countershaftgearset with a front clutch carrier rotating coaxially with the frontplanetary gearset for selectively transferring power from the elementsof the front planetary gearset and a rear clutch carrier for selectivelyconnecting the countershaft gearset and the rear dual pinion planetarygearset to transfer power to the output shaft in response to selectivelyoperating the transmission controls.

The objects of this invention are accomplished by providing an inputdrive shaft and an output driven shaft rotating coaxially within atransmission housing. A front planetary gearset is connected to theinput shaft and a rear dual pinion planetary gearset is selectivelyconnected to the output shaft and rotates coaxially therewith. An inputclutch carrier and an output clutch carrier also rotate coaxially withthe planetary gearsets and each have a gear constantly engagingcountershaft gears for transmitting power around the planetary gearsets.The front clutch carrier has friction members individually connected toeach one of the ring gear, the sun gear and the planetary carrier toselectively transfer power from the front planetary gearset to the frontclutch carrier to selectively transfer power through the countershaftgearset or the front planetary gearset. A rear clutch carrier rotatescoaxially with the dual pinion rear planetary gearset and has a frictionmember on the sun gear and the planetary carrier to selectively transmitpower from the countershaft gearset and the rear dual pinion planetarygearset to the output shaft. Control means selectively actuate one ormore of the plurality of clutches on the clutch carriers or a brakemounted on the transmission housing to selectively engage clutches orthe brake for transmission of power through the transmission for desiredspeed ratios.

The preferred embodiments of the invention have been illustrated in theattached drawings.

FIG. 1 illustrates a cross section view of the transmission.

FIG. 2 is a cross section view taken on line Il-ll of FIG. 1.

FIG. 3 is a cross section view taken on line IlIllI of FIG. 1.

FIG. 4 is a schematic illustration of the hydraulic system and actuatingcontrol for the hydraulic transmis- SlOIl.

FIG. 5 is a table of the gear range, clutches actuated, and speed ratioof the transmission.

Referring to FIG. 1, a transmission housing 1 is bolted to the end plate2 by a plurality of bolts 3. The end plate 2 provides bearing supportfor the shafts and supports the cover plate 4 which is fastened by aplurality of bolts 5 carrying a seal 106 sealing the end of thetransmission.

The end plate 2 embraces the bearing assembly 6 which rotatably supportsthe left hand end of the front clutch carrier 7. The end plate 2 alsoembraces the bearing assembly 8 which rotatably supports theintermediate portion of the front clutch carrier 7.

The left hand end of the input drive shaft 9 is rotatably supported onthe bearing assembly 10 which is held in position by the retainer rings11 and 12 on the inner periphery of the front clutch. carrier 7.

The right hand end of the input drive shaft 9 forms a power take-offshaft with a spline 13 on its right hand end. Immediately to the left ofthe spline 13, the shaft 9 is journaled in the bearing assembly 14 whichis rotatably supported within the quill shaft 15. The quill shaft 15 oroutput driven shaft is rotatably mounted in the bearing assembly 16which is carried on the bearing support sleeve 17. The bearing supportsleeve extends into the transmission and supports the bearing assembly18 which is embraced by the rear clutch carrier 19. The bearing supportsleeve 17 encircles the needle bearing assembly 20 which rotatablysupports the quill shaft 15 radially inward from the bearing assembly18. The output driven shaft or quill shaft 15 supports the rear dualpinion planetary gearset 21. The front planetary gearset 22 is supportedon the input drive shaft $7.

The front clutch carrier 7 is braked by the brake 23 mounted internallyof the end plate 2 and having a friction disk carried on the frontclutch carrier 7.

The clutch 24, clutch 25, and clutch 26 selectively clutch a frictionelement carried on the sun gear 46, the planetary carrier 49, and thering gear 67 of the front planetary gearset 22.

The clutch 27 and 28 selectively clutch a friction element carried onthe planetary carrier and the sun gear 76 of the rear dual pinionplanetary gearset 21.

The front clutch carrier 7 carries the gear which is bolted by aplurality of bolts 31 to the brake hub 32 and the rotor 33. The rotor 33extends through the end plate 2 and is rotatably supported on thebearing assembly 6. The gear 30 meshes with a gear 34 splined to thecountershaft 35. The countershaft 35 is also splined to the gear 36which meshes with gear 37 on the rear clutch carrier 19. The gear 37 isbolted to the rear clutch carrier 19 by a plurality of bolts 38. Thecountershaft 35 is rotatably supported on the bearing assembly 39received within the opening 40 and the end plate 2. The bearing assembly39 is retained by the snap ring 41 and the bearing nut 42 positioned onthe end of the bearing 39 and the countershaft 35.

The right hand end of the countershaft 35 is similarly mounted in abearing assembly 43 in the transmission housing 1. The bearing assembly43 is maintained in position by the snap ring 44 and the bearingretainer nut 45.

The front planetary gearset 22 includes a sun gear 46 which is splinedto the input shaft 9. The spline 47 also carries the clutch hub 48. Theplanetary carrier 49 on the input planetary gearset 22 supports the pin50. The

.pin 50 is embraced by the bearing assemblies 51 and 52. The planetgears 53 are in constant mesh with the sun gear 46 and the ring gear 67.The ring gear 67 has a gear facing on its inner periphery and togetherwith ring gear 68 for the rear planetary gearset 21 forms the integralgear 54.

The clutch hub 48 is splined on its external periphery to receive aclutch disk 55 which frictionally engages a mating clutch disk 56 whichis carried in the rotor 33. The rotor 33 forms a hydraulic cylinder 57which receives a hydraulic piston 58 which defines the pressurizingchamber 59 in communication with the hydraulic fluid conduit 150. Theclutch 24 when actuated frictionally engages the clutch disks 55 and 56and clutches the sun gear 46 with the clutch carrier 7.

The planetary carrier 49 is splined on its external periphery to receivethe clutch disk 61 which frictionally engages the clutch disk 62received in the annulus 63 which forms a hydraulic cylinder 64. Thehydraulic cylinder 64 receives the hydraulic piston 65 which forms thehydraulic pressurizing chamber 66. When the clutch 25 is actuated, thefront clutch housing 7 is clutched to the planetary carrier 49.

The ring gear 67 of the front planetary gearset is integral with thering gear 68 of the rear planetary gearset and is formed by the integralring gear 54. The integral ring gear 54 forms a gear facing on itsexternal periphery and is embraced by the plurality of clutch disks 69on its external periphery. The clutch disks 69 frictionally engagemating clutch disks 70 which are seated on the splined portion of theannulus 71. The annulus 71 forms a hydraulic cylinder 72 which receivesthe hydraulic piston 73 which defines the pressurizing chamber 74. Whenthe clutch 26 is actuated, the clutch disks 69 and 70 frictionallyengage each other and the ring gear 67 is clutched to the input clutchcarrier 7. It is also noted that the backup plate 174 forms the reactionmember for the clutch 26. A plurality of bolts 75 extend through theannulus 71, 63 and the rotor 33 to fasten the assembly to form the frontclutch carrier.

The rear planetary gearset 21 is also rotatably mounted coaxially withthe shafts 9 and 15. The sun gear 76 of the rear planetary gearset issplined to the quill shaft 15. The splined portion 77 on the quill shaft15 also receives the carrier 49 of the input planetary gearset 22. Acontinuation of the spline 77 also receives a mating clutch housing 78.The integral ring gear 54 is supported on the annulus 80 which isretained axially by the snap rings 81 and 82. The sun gear 76 engagesthe inner planet pinion 83 which is in constant mesh with the outerplanet pinion 84. The outer planet pinion 84 engages the ring gear 68.Consequently, the sun gear and ring gear simultaneously rotate in thesame direction in contrast to the planetary arrangement of the frontplanetary gearset in which the ring gear and sun gear are simultaneouslyrotating in opposite directions.

A planetary carrier 85 carries a plurality of pins 86 which are embracedby bearing assemblies 87 and 88. The bearing assemblies 87 and 88provide a bearing support for the outer planet pinions 84. The planetarycarrier 85 also supports a plurality of pins 90 embraced by a pluralityof bearing assemblies 91 and 92 which rotatably support the inner planetpinions 83. It is noted that the inner planet pinions 83 engage the Sungear while the outer planet pinions 84 engage the ring gear 68 of therear planetary gearset.

A clutch 27 includes a plurality of clutch disks 92 which frictionallyengage a plurality of clutch disks 93 carried on the annulus 94. Theannulus 94 forms a hydraulic cylinder 95 and a piston 96 which form apressurizing chamber 97 for actuating the clutch. The reaction plate 98is bolted by a plurality of bolts 99 which fasten the annulus 94 torotor 100 to form the assembly comprising the rear clutch carrier 19.The clutch hub 78 supports a plurality of clutch disks 101 interposedbetween the clutch disks 102 which are supported on a spline 103 of therotor 100. A rotor 100 forms a hydraulic cylinder 104 which receives thehydraulic pistons 105 forming pressurizing chamber 106. The pressurizingchamber is connected to the conduits l07 and 108 which are incommunication with the hydraulic actuating circuit for the clutches andthe brake. The rear clutch carrier 19 is rotatably supported on thebearing assemblies 18 and 109.

Referring to FIG. 4, the hydraulic system for actuating the power shifttransmission is illustrated. The pump 110 receives hydraulic fluidthrough conduit 111 from reservoir 112. The pump pressurizes fluid inthe conduit 1 13 which is connected to the brake and clutch actuationcontrol valve 114. Return fluid is returned through the return conduit115.

The conduit 116 is in communication with the brake 23. The conduits 117,1 18, and 119 are in communication with the clutches 24, 25 and 26respectively on the front clutch carrier. The conduits 120, 121 are incommunication with the clutches 27 and 28 on the rear clutch carrier 19respectively. The brake and clutch actuation control valve 114selectively actuate one or more of a plurality of brakes and clutches23, 24, 25, 26, 27 and 28. The operation of the transmission will bedescribed in the following paragraphs.

Power is applied to the input drive shaft 9 and power is taken off thesame shaft which is provided with a power take-off spline. Powertransmitted through the transmission is taken off the output quill shaft15.

When the transmission is in reverse, the clutches 26 and 28 areactuated. The power is transmitted from the sun gear 46 through theplanet pinion 53 to the ring gear 67 of the front planetary gearset 22and the ring gear 68 of the second planetary gearset 21, thence throughthe dual pinion planetary gearset which causes a negative torque andreverse rotation on the output shaft. Simultaneously with thecounter-rotation of the ring gear 67, the clutch 26 engages the frontclutch carrier 7 causing the counter-rotation of the clutch carrier 7which is transmitted through the countershaft gearset to the rear clutchcarrier 19 and through clutch 28 to produce a reaction torque on theoutput shaft thereby providing a resultant reverse rotation of theoutput shaft.

When the transmission is placed in the first forward speed, clutches 26and the brake 23 are engaged. The positive torque applied to the sungear 46 produces a negative torque or reaction torque on the ring gear67. Since the clutch 26 is engaged and the front clutch carrier 7 islocked to the transmission housing by the brake 23, the carrier 49 onthe input clutch housing rotates on the inside of the ring gear 67causing the carrier 49 to drive the sun gear 76 of the rear dual pinionplanetary gearset 21. The sun gear 76 is connected to the output shaft15 and accordingly, it drives the output shaft 15 with a high torqueratio in the forward direction; in other words, the same direction ofrotation as the input shaft 9.

When the transmission is shifted to the second forward speed brake 23 isengaged and the clutch 27 is engaged. Braking of the front clutchcarrier 7 also locks the countershaft gearset with the rear clutchcarrier 19. Clutching of the rear clutch carrier 19 through clutch 27causes the planetary carrier 85 of the rear planetary gearset 21 toremain stationary while the positive torque applied to the input shaft 9drives through the front planetary gearset 22. A negative torque isapplied to the ring gear 67 which in turn is transmitted to the ringgear 68. With the planetary carrier :85 of the rear planetary gearset 21locked, the negative reaction torque transmitted through the rearplanetary gearset 21 is transmitted as the reaction torque tothe sungear 46. A positive driving torque is transmitted from the sun gear 46to the carrier 49 which drives the sun gear 76. The result in torque isa positive rotation with a high torque output on the output drive shaft15.

When the transmission is positioned in the third forward speed, theclutches 26 and 27 are actuated. A positive driving torque from theinput shaft 9 is transmitted from the sun gear 46 to the carrier 49 tothe output shaft 15. Simultaneously, a reaction torque is generatedwhich is a negative torque transmitted through the clutch 26 through thecountershaft gearset 140 and the clutch 27 to the planetary carrier 85of the second planetary gear set 21, as well as the negative torquebeing transmitted through the ring gears 67 and 68 to the dual pinionplanetary carrier 85 of the rear planetary gearset. The result is apositive torque driving the output shaft 15.

When the transmission is positioned in the fourth forward speed, theclutches 25 and 27are engaged. A positive torque is applied to the inputdrive shaft 9 through the sun gear 46 driving the carrier 49 in forwarddirection. This produces a torque transmitted to the sun gear 76 of therear planetary gearset 21. Simultaneously a negative reaction torque istransmitted through the ring gear 67 to drive the ring gear 68 of thesecond planetary gearset 21. A reaction torque is also transmitted fromthe input planetary carrier 7 through the countershaft gearset 140 tothe output clutch carrier 19 which is applied to the planetary carrier85. The result is a 6 positive torque and forward drive to the outputdrive shaft 15.

When the transmission is positioned in the fifth forward speed, theclutches 24 and 27 are engaged. The input drive shaft 9 drives the sungear 46 producing a positive torque which is transmitted through carrier49 to the sun gear 76 of the rear planetary gearset. Engagement ofclutch 24 produces a transmission of positive torque through clutch 24through front clutch carrier 7 and through the countershaft gearset 140to the rear clutch carrier 19. With clutch 27 engaged, the positivetorque is transmitted through the planetary carrier of the rearplanetary gearset 21. Negative reaction torque is also transmittedthrough the ring gears 67 and 68 with the resultant torque on the sungear in the positive direction providing forward speed of rotation forthe output driven shaft 15.

When the transmission is positioned in the sixth gear range, theclutches 24 and 26 are engaged. With the clutch 24 engaged, the sun gear46 of the front planetary gearset 22 is locked in the front clutchcarrier 7. The ring gear 67 of the front planetary gearset is alsolocked to the front clutch carrier 7 and the planetary gearset 22 islocked. The forward rotation and positive torque applied to the inputdrive shaft 9 is transmitted directly through the carrier 49 to the sungear 76 of the rear planetary gearset 21 providing low torque and highforward speed of rotation on the output driven shaft 15 of thetransmission.

It is further noted that the input drive shaft 9 is integral with thepower take-off shaft and forms the spline 13 adapted for connection to apower take-off assembly. The output drive shaft 15 is provided withmeans for transmitting power output from the transmission. Thetransmission provides for simultaneous power take-off with each gearratio of the transmission. The transmission, accordingly, will beprovided with suitable clutch and braking means with a power take-offassembly for engaging and disengaging of the power take-off assembly.The clutches provide smooth transitions of power, since no more than onetransition of a clutch is required to make any shift in the upshiftingand downshifting of the gear ratios of the transmission. The relativespeeds of the clutch plates are low which reduces roughness intransition of power in the sequence of gearshifts as set forth above.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A transmission comprising an input shaft and an output shaftrotatably mounted in a transmission case, a front planetary gearsethaving a sun gear driven by said input shaft, a rear planetary gearsethaving a sun gear connected to a planetary carrier of the frontplanetary gearset and driving said output shaft, means connecting thering gear of said front planetary gearset with the ring gear of saidrear planetary gearset, a front clutch carrier rotatably mounted forcoaxial rotation with said input shaft, a rear clutch carrier mountedfor coaxial rotation with said output shaft, said front planetarygearset including the elements of a sun gear, a ring gear, and aplanetary carrier, a plurality of clutches mounted on said front clutchcarrier for clutching said carrier to said elements of said frontplanetary gearset, said rear planetary gearset defining a dual pinionplanetary gearset including dual planetary pinions and having a commondirection of rotation of the ring gear and the sun gear, said rearplanetary gearset including the elements of a planetary carrier, a ringgear, a sun gear, two clutches mounted on said rear clutch carrier forclutching said rear clutch carrier with two of said elements of saidrear planetary gearset, a brake mounted on said transmission case forclutching said front clutch carrier to said transmission case, a drivegear connected to said front clutch carrier, a driven gear connected tosaid rear clutch carrier, a countershaft gearing for engagement withsaid drive gear and said driven gear thereby providing a countershaftgearset between said clutch carriers, means for selectively actuating atleast one of said brakes and clutches to thereby selectively provide oneof a plurality of power paths and gear ratios through said transmission.

2. A transmission as set forth in claim 1 wherein said front clutchcarrier carries a clutch having a friction member connected to the ringgear of said front planetary gearset and said rear clutch carriercarries a clutch having a' friction member connected to the sun gear ofsaid rear planetary gearset to thereby provide positive torque andforward rotation from the planetary carrier of said front planetarygearset to the output shaft and a negative reaction torque through thering gear and the countershaft gearset to provide a reverse rotation ofthe output shaft.

3. A transmission as set forth in claim 1 wherein said brake on saidtransmission case includes a friction member connected to the frontclutch carrier and said front clutch carrier includes a clutch having afriction member connected to the ring gear of the front planetarygearset for braking the front clutch carrier and providing a positivetorque through the carrier of the front planetary gearset to the sungear of the rear planetary gearset to provide a forward speed, hightorque output.

4. A transmission as set forth in claim 1 wherein said brake on saidtransmission case includes a friction member connected to the frontclutch carrier and said rear clutch carrier includes a friction memberconnected to the planetary carrier of the rear planetary gearset tothereby provide a positive driving torque transmitted from the planetarycarrier of the first planetary gearset to the sun gear of the rearplanetary gearset and a negative reaction torque through the ring gearsof said first and second planetary gearsets to thereby provide apositive high torque output on the output drive shaft.

5. A transmission as set forth in claim 1 wherein said front clutchcarrier includes a clutch having a friction member connected to the ringgear of the front planetary gearset and the rear clutch carrier includesa friction member connected to the planetary carrier of the rearplanetary gearset to thereby provide a positive torque driving from theplanetary carrier of the front planetary gearset to the sun gear of therear planetary gearset and a negative torque transmitted through thering gears and the countershaft gearing to provide a reaction torque onthe ring gear and the planetary carrier of the rear planetary gearset tothereby provide a forward positive torque output on said transmission.

6. A transmission as set forth in claim 1 wherein said front clutchcarrier includes a clutch having a friction member connected to theplanetary carrier of the front planetary gearset and said rear clutchcarrier includes a clutch having a friction member connected to theplanetary carrier of the rear planetary gearset to thereby provide apositive torque transmitted from the planetary carrier of the frontplanetary gearset to the sun gear of the rear planetary gearset to theoutput shaft and a negative reaction torque transmitted through the ringgears and a negative reaction torque transmitted through the rearplanetary carrier of the rear planetary gearset to thereby provide aresultant torque of positive rotation in the output shaft.

7. A transmission as set forth in claim 1 wherein said front clutchcarrier includes a clutch having a friction member connected to the sungear of the front planetary gearset, said rear clutch carrier includes aclutch having a friction member connected to planetary carrier of therear planetary gearset to thereby provide a positive torque of forwardrotation transmitted through the planetary carrier of the frontplanetary gearset to the sun gear of the rear planetary gearset and theoutput shaft.

8. A transmission as set forth in claim 1 wherein said front clutchcarrier includes a clutch having a friction member connected to the sungear of the front planetary gearset and a clutch having a frictionmember connected to the ring gear of said front planetary gearset tothereby lock the front planetary gearset and provide a direct drivethrough the front planetary gearset to the output drive shaft providinga positive low output torque of forward rotation on the output shaft ofthe transmission.

9. A transmission as set forth in claim 1 wherein said transmissionincludes an input drive shaft integral with and including a powertake-off shaft including means adapted for connection to the powertake-off shaft.

10. A transmission as set forth in claim 1 wherein said output shaftdefines a quill shaft rotatably receiving said input shaft to therebyprovide coaxial rotation of the input and output shafts.

1. A transmission comprising an input shaft and an output shaftrotatably mounted in a transmission case, a front planetary gearsethaving a sun gear driven by said input shaft, a rear planetary gearsethaving a sun gear connected to a planetary carrier of the frontplanetary gearset and driving said output shaft, means connecting thering gear of said front planetary gearset with the ring gear of saidrear planetary gearset, a front clutch carrier rotatably mounted forcoaxial rotation with said input shaft, a rear clutch carrier mountedfor coaxial rotation with said output shaft, said front planetarygearset including the elements of a sun gear, a ring gear, and aplanetary carrier, a plurality of clutches mounted on said front clutchcarrier for clutching said carrier to said elements of said frontplanetary gearset, said rear planetary gearset defining a dual pinionplanetary gearset including dual planetary pinions and having a commondirection of rotation of the ring gear and the sun gear, said rearplanetary gearset including the elements of a planetary carrier, a ringgear, a sun gear, two clutches mounted on said rear clutch carrier forclutching said rear clutch carrier with two of said elements of saidrear planetary gearset, a brake mounted on said transmission case forclutching said front clutch carrier to said transmission case, a drivegear connected to said front clutch carrier, a driven gear connected tosaid rear clutch carrier, a countershaft gearing for engagement withsaid drive gear and said driven gear thereby providing a countershaftgearset between said clutch carriers, means for selectively actuating atleast one of said brakes and clutches to thereby selectively provide oneof a plurality of power paths and gear ratios through said transmission.2. A transmission as set forth in claim 1 wherein said front clutchcarrier carries a clutch having a friction member connected to the ringgear of said front planetary gearset and said rear clutch carriercarries a clutch having a friction member connected to the sun gear ofsaid rear planetary gearset to thereby provide positive torque andforward rotation from the planetary carrier of said front planetarygearset to the output shaft and a negative reaction torque through thering gear and the countershaft gearset to provide a reverse rotation ofthe output shaft.
 3. A transmission as set forth in claim 1 wherein saidbrake on said transmission case includes a friction member connected tothe front clutch carrier and said front clutch carrier includes a clutchhaving a friction member connected to the ring gear of the frontplanetary gearset for braking the front clutch carrier and providing apositive torque through the carrier of the front planetary gearset tothe sun gear of the rear planetary gearset to provide a forward speed,high torque output.
 4. A transmission as set forth in claim 1 whereinsaid brake on said transmission case includes a friction memberconnected to the front clutch carrier and said rear clutch carrierincludes a friction member connected to the planetary carrier of therear planetary gearset to thereby provide a positive driving torquetransmitted from the planetary carrier of the first planetary gearset tothe sun gear of the rear planetary gearset and a negative reactiontorque through the ring gears of said first and second planetarygearsets to thereby provide a positive high torque output on the outputdrive shaft.
 5. A transmission as set forth in claim 1 wherein saidfront clutch carrier includes a clutch having a friction memberconnected to the ring gear of the front planetary gearset and the rearclutch carrier includes a friction member connected to the planetarycarrier of the rear planetary gearset to thereby provide a positivetorque driving from the planetary carrier of the front planetary gearsetto the sun gear of the rear planetary gearset and a negative torquetransmitted through the ring gears and the countershaft gearing toprovide a reaction torque on the ring gear and the planetary carrier ofthe rear planetary gearset to thereby provide a forward positive torqueoutput on said transmission.
 6. A transmission as set forth in claim 1wherein said front clutch carrier includes a clutch having a frictionmember connected to the planetary carrier of the front planetary gearsetand said rear clutch carrier includes a clutch having a friction memberconnected to the planetary carrier of the rear planetary gearset tothereby provide a positive torque transmitted from the planetary carrierof the front planetary gearset to the sun gear of the rear planetarygearset to the output shaft and a negative reaction torque transmittedthrough the ring gears and a negative reaction torque transmittedthrough the rear planetary carrier of the rear planetary gearset tothereby provide a resultant torque of positive rotation in the outputshaft.
 7. A transmission as set forth in claim 1 wherein said frontclutch carrier includes a clutch having a friction member connected tothe sun gear of the front planetary gearset, said rear clutch carrierincludes a clutch having a friction member connected to planetarycarrier of the rear planetary gearset to thereby provide a positivetorque of forward rotation transmitted through the planetary carrier ofthe front planetary gearset to the sun gear of the rear planetarygearset and the output shaft.
 8. A transmission as set forth in claim 1wherein said front clutch carrier includes a clutch having a frictionmember connected to the sun gear of the front planetary gearset and aclutch having a friction member connected to the ring gear of said frontplanetary gearset to thereby lock the front planetary gearset andprovide a direct drive through the front planetary gearset to the outputdrive shaft providing a positive low output torque of forward rotationon the output shaft of the transmission.
 9. A transmission as set forthin claim 1 wherein said transmission includes an input drive shaftintegral with and including a power take-off shaft including meansadapted for connection to the power take-off shaft.
 10. A transmissionas set forth in claim 1 wherein said output shaft defines a quill shaftrotatably receiving said input shaft to thereby provide coaxial rotationof the input and output shafts.